Uni Filter NU-2221ST Two-Stage Foam Air Filter for Yamaha MX250 MX400

The Uni Filter NU-2221ST is a two-stage polyurethane foam air filter designed as a direct-fit replacement for the Yamaha MX250 and MX400. Built for off-road performance, it delivers superior engine protection and maximized airflow compared to standard OEM paper filters.

Two-Stage Filtration Technology:

• Coarse outer layer — captures large dirt and dust particles before they reach the engine
• Fine-pore inner layer — provides ultimate protection against fine particulates and grit
• Two-stage design separates for thorough cleaning and re-oiling
• Most filters feature Uni's Ultra Seal grease groove on the sealing surface for an airtight fit in the stock airbox

Performance & Durability:

• Fits directly into the stock airbox like the OEM filter — no modifications required
• Cleanable and reusable indefinitely — clean with grease-cutting dish soap, re-oil, and reinstall
• Constructed from open-cell polyurethane foam oiled with specially developed filter oil
• Made in the U.S.A.

Uni Filter's two-stage design has been the choice of championship-winning race teams and serious off-road enthusiasts for decades. The NU-2221ST delivers the proven performance and reliability that Uni Filter has built its reputation on since entering the industry in 1969.